1. Field of the Invention
The present invention relates to a content transmitting apparatus, a content transmitting method, and a content transmitting program. More particularly, the invention relates to a content transmitting apparatus, a content transmitting method, and a content transmitting program for transmitting content data distributed in streaming mode to receiving apparatuses such as recorders via a network.
2. Description of the Related Art
Recent years have witnessed growing acceptance of the so-called home network connecting household electrical appliances with a computer for communication therebetween.
This type of network typically involves getting a content transmitting apparatus to receive content data distributed in streaming mode from broadcasting stations and to transmit the received content data to receiving apparatuses such as a display device and a recorder via the network, whereby the received content data is stored.
In many cases, content data is offered in digitized form. Such digital content data is relatively easy to copy or tamper with.
To forestall such eventualities, content data is typically transmitted to the home network in a copyright-protected manner according to DTCP-IP (Digital Transmission Content Protection over Internet Protocol), an adaptation of DTCP (Digital Transmission Content Protection) developed by DTLA (Digital Transmission Licensing Administrator) to IP (Internet Protocol) interfaces.
When transmitting content data in streaming mode to receiving apparatuses, the content transmitting apparatus generally utilizes RTP (Real Time Protocol)/UDP (User Datagram Protocol). The protocols allow the content transmitting apparatus to transmit content data at high speeds to the receiving apparatuses.
On the home network, meanwhile, household electrical appliances are connected increasingly with a computer under HTTP (Hyper Text Transmission Protocol)/TCP (Transmission Control Protocol), as proposed by DLNA (Digital Living Network Alliance).
In this case, the content transmitting apparatus transmits content data under HTTP/TCP so that the data may be transmitted to the receiving apparatuses in highly reliable fashion.
If any receiving apparatus fails to receive the content data, then that receiving apparatus transmits a retransmission request to the content transmitting apparatus. In such a case, it takes time for the content transmitting apparatus to retransmit the content data. The retransmission can result in a delay of the content data being transmitted in streaming mode.
Some content transmitting apparatuses incorporate a buffer to accommodate the content data being distributed by a broadcasting station. When a predetermined amount of content data has been accumulated following the last occurrence of a delay, the accumulated content data is discarded to ensure required levels of real-time performance. One such content transmitting apparatus is proposed in Japanese Patent Laid-open No. 2005-51709.